For automotive engineers looking to reduce vehicle weight, metal-to-plastic conversion is a win-win. At the highest level, injection plastic molds are capable of producing multiples of millions of parts required for automotive programs with ease. Typically, a single tool can support a program for its entire life-cycle, meaning you only must go through the cost and design of tooling just once.

In traditional metal fabrication, you have stamping and die casting, both of which require tool refurbishment, at what can amount to a very significant cost. Although injection mold tooling can be relatively expensive, it is not more expensive than die cast tools and/or stamping tools.

Typically, injection molds will last many times longer than metal tooling. Injection mold tooling are also more flexible than other types of tools, allowing you to incorporate many types of features into a part so that no secondary machining, coating and/or forming is required after the molding operation. And depending on the type of plastic material you select; you can realize excellent strength to weight properties.

Why is that important?

Metal has been used for decades now to machine and fabricate parts that need to last long past the product’s life cycle. Today, metal replacement parts, better known as metal-to-plastic replacement technology, offers a lighter, more cost effective solution that is often superior to the metal part it replaces.

Take for instance the cylinder head cover pictured. It has undergone a metal-to-plastic transformation, featuring multiple cable management mounts, coupled with the elimination of the spark plug tube mounting point, which has vastly decreased noise from the engine.

But most importantly, its weight has decreased 47% - a significant weight savings by automotive manufacturing standards.

Design support is critical

Selecting the right injection molding plastic resource is critical, especially for companies that do not have in-house plastic expertise. Support engineers can ensure that the plastic part is properly designed for optimum molding capability, and look for opportunities to combine multiple parts into one, eliminating cost and manufacturing operations down the line. Plastic engineers can also support the design process with computer aided analysis, such as mold flow and finite element analysis (FEA).

Finally, plastic engineers can help with selecting the correct plastic resin, noting the user environment and required chemical resistance, operating temperature range, and whether there needs to be electrical properties such as conductivity, thermal properties such as heat dissipation and mechanical strength. Plastics offer more functionality with less weight. With plastics, there is a freedom of design not found in metal parts.

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